1. Field of the Invention
The present invention relates to the field of diagnostic systems for the maintenance of gas turbine engines.
2. Brief Description of the Prior Art
Gas turbine engines are widely used in aircraft, including airplanes and helicopters, including turbo shaft and turbo prop craft, and are even employed to power missiles. Because of the safety requirements demanded by the operation of such craft, and the reliability necessitated, testing must be done routinely to ensure that the engine operation is sufficient.
Generally, gas turbine engines operate by igniting a mixture of injected fuel and compressed air within a combustion chamber or assembly and then channeling the output of exiting combustion gases to drive a turbine stage. The engine can be mounted within an outer housing. The outer housing can include a duct formed in part by an inner housing, through which a flow of air is directed. The airflow can be directed with a fan to exhaust with a portion of the airflow being directed to a high-speed compressor. Air from the compressor is directed to a combustor for combustion with injected fuel. Additionally, some engines will route air not taken up by the compressor to exhaust in order to increase thrust.
Gas turbine engines generally operate by using a continuous combustion process. The inlet air temperature and pressure is raised by a compressor, after which the air is moved into a burner or combustion chamber. Fuel is injected into the chamber and then combusted to raise the air temperature. The heated fuel air mixture, now under a high pressure and at a high temperature, is expanded and cooled through a turbine. The turbine speed can be controlled by the amount of fuel that is injected into the combustion chamber, and the amount of high pressure air which passes therethrough. Gas turbine engines may have a single moving rotor or can contain multiple rotors, such as, for example, wherein the engine includes a gas generator rotor and a power turbine rotor. Although these rotors may be the only moving parts, gas turbine engines must rely on a variety of parameters to function and meet the load and operating demands.
A variety of engine tests are performed in order to maintain the engine in an operative condition. Usually, the testing engineer will attach instruments to various locations on the engine to obtain readings of engine operation parameters. The engineer will operate the engine and read numerical data from the instruments. The values obtained from the readings must then be compared to determine whether the engine will meet the specified parameters which enable it to be placed in operation.
Testing often requires a plurality of instruments. The operator or engineer uses the instruments to obtain readings of the engine parameters when the engine is operated under controlled conditions which the operator also records. The operator utilizes the readings taken from the instruments to provide further information concerning a test parameter. The testing usually requires the operator to ascertain a given parameter, and then take a reading of a subsequent parameter. The parameters generally are read from instruments successively, and cover a time span of operation for the engine. The operator may therefore recheck parameters which appear to be excessive or out of the expected range. However, this will require a recheck of additional values as well, necessitating a repeat of the entire test procedure.
While there exist instruments which will display digital information or can provide a reading on a dial, these also require that the user view the data at a particular point in time. Where multiple instrumentation is used to measure various parameters, the operator usually will record the data, and when each parameter has been ascertained compare the results to determine engine performance.
A change in the engine operation can affect the parameters being analyzed, as can a change in the engine testing environment. The environment, particularly the surrounding temperature and atmospheric pressure, can affect the operation of the gas turbine engine. The test results obtained with instruments must be considered with respect to the atmospheric and temperature conditions at the time taken. For example, if the surrounding air temperature increases or decreases by even a couple of degrees, the engine operating requirements may also be altered. In such a circumstance, if the operator did not note a temperature change in the environment throughout a testing cycle, the engine might be passed or failed, incorrectly.
A need exists for a real time analysis system which provides visual information representative of a grouping of results for an engine which is being tested.